[Newbie] Gear configuration on Chinese lathe

[Jim F]

Ultimately I want to learn how to thread and chamber my own rifle barrels. I’ve always been drawn to machining and thought why not. I know this sounds crazy but I wanna make a small gasoline engine. However first things first and I have to make tools. My first real project is a spider for my spindle. That requires internal threading but for that I had to learn how to set my gears up. Next I must learn external threading so I bought some round bar and tubing to start practicing.
I’m excited about learning how to do these things and wish they had a course or two offered locally. However the community college doesn’t have anything so I thought a place like this would be full of practical knowledge and tons of real hands on experience. At this point I have nothing to contribute but hopefully in several months I’ll be able to share what I’ve learned with others. My journey has begun and all because of your assistance. I’ll post my results after I actually cut some threads but I’m confident you’ve put me on the right path. I appreciate all of your help and I can’t thank you enough. I’m probably rambling a bit so I’m gonna stop here. Thanks again and happy holidays to you and yours

Threading is not as hard as you think.
Joe Pie, Abom79 and OX Tool all have very good videos about such.
If you want to do barrel and chamber work, your going to need a bigger lathe.....

 

[jcmullis2]

I’ve watched several of joe’s YouTube videos. That man knows his stuff and is a good teacher. I like the ass backwards threading method of his. I’m waiting on a 4 jaw so I can fit a qctp and then I plan to use Joe’s threading method. My lathe didn’t come with a threading dial so I have to find a way to make one for a metric lead screw cutting imperial threads. I’ll be turning the lathe off and backing out and reversing for a while I’m sure.
Thanks for the suggestions and I’ll check those fellas out on YouTube

 

[GrumpyGrandpa]

Thank you for this post, I am a newbie also and I was trying to wrap my head around this also with my MX210V. Now it to the shop to see if I can make this happen with my new found knowledge.

 

[weston1968]

I just posted a program to calculate the gears for any thread metric or Imperial where you can put in the gears you have and it will return the best combination and accuracy.

 

[Rowdy12]

Hi guys, I recently bought a Vevor "mini lathe 220x500mm" the one with the gearbox in the lower left.
The name on the manual is MX-600A, but the spindle gear side looks exactly like the pic Lo-Fi posted in #11.
It comes with a 2mm/revolution drive spindle and a neat three gear levershifted-gearbox reading "low", "middle" and "high"
(internally done as transmission ration of 1:2 , 1:1 and 2:1)

I, too, found out that the cheat-sheet with the gearing needed for thread cutting is fundamentally wrong
(there are sprocket combos that won't fit, the ratios are ludicrally off, etc).

I got the following sprockets with the lathe: 24 30 33 40 50 52 60 66 80 84 102
and on the main spindle there is a 56 teeth driving sprocket.

I shoved the data into an ORACLE database, measured geometry limits (e.g. how many sprocket-theeth the swiveling axle carrier can accomodate)
and had the database do a brute force attack to find gearings that would produce correct metric and imperial threads.
So when I let the computation add a 127 teeth sprocket (as if I had bought it myself) to the pool above the best TPIs one can create are

TPI setting_56_127 A B C D E
---------- ---------------------------------------------
9.00055804 re fast Spindle 56:127 80 24 50 E2
12.000744 re fast Spindle 56:127 60 33 50 E2
18.0011161 re fast Spindle 56:127 24 60 30 E2
24.0014881 re fast Spindle 56:127 24 60 40 E2
30.0018601 re fast Spindle 56:50 24 52 127 E2
36.0022321 re fast Spindle 56:60 24 50 127 E2
48.0029762 re fast Spindle 56:80 24 40 127 E2
60.0037202 re med Spindle 56:50 24 52 127 E2
72.0044643 re med Spindle 56:60 24 50 127 E2
96.0059524 re med Spindle 56:80 24 40 127 E2
112.991621 re slow Spindle 56:102 52 24 127 E2
120.00744 re slow Spindle 56:50 24 52 127 E2
127 re slow Spindle 56:80 24 60 84
144.008929 re slow Spindle 56:60 24 50 127 E2
192.011905 re slow Spindle 56:80 24 40 127 E2

which means not one single TPI (except 127 TPI, duh) can be created wioht the supplied sprockets and an additional 127 T sprocket.
But there is hope! If one get himself a 127 Modul 1 sprocket and give it a 45 mm bore (it#s a lathe, right) and somehow manages to add a keyway and puts the sprocket right onto the main spindle (instead of the dreaded 56T) then it's christmas, you can configure basically all TPI threads you'll ever need, and each w/o any compromise regarding precision :
TPI setting_127_-10000 A B C D E
---------- ---------------------------------------------
- 1 mi fast Spindle 127:80 40 66 33
- 2 re fast Spindle 127:50 30 102 24
- 3 re fast Spindle 127:80 40 84 30
- 4 re fast Spindle 127:40 30 84 60
- 5 re fast Spindle 127:50 30 80 60
- 6 re fast Spindle 127:60 40 66 80
- 7 re fast Spindle 127:84 24 80 40
- 8 re fast Spindle 127:60 30 66 80
- 9 re slow Spindle 127:60 40 84 30
- 10 re fast Spindle 127:80 24 84 60
- 11 re fast Spindle 127:80 24 84 66
- 12 re med Spindle 127:60 40 66 80
- 13 re med Spindle 127:52 24 84 60
- 14 re fast Spindle 127:80 24 60 84
- 15 re slow Spindle 127:60 24 102 30
- 16 re med Spindle 127:60 30 66 80
- 17 re fast Spindle 127:80 24 50 102
- 20 re med Spindle 127:80 24 84 60
- 21 re med Spindle 127:60 24 66 84
- 22 re med Spindle 127:80 24 84 66
- 24 re slow Spindle 127:60 40 66 80
- 25 re slow Spindle 127:50 24 84 60
- 26 re slow Spindle 127:52 24 84 60
- 28 re med Spindle 127:80 24 60 84
- 32 re slow Spindle 127:60 30 66 80
- 33 re slow Spindle 127:60 24 80 66
- 34 re med Spindle 127:80 24 50 102
- 35 re slow Spindle 127:84 24 80 50
- 40 re slow Spindle 127:80 24 84 60
- 42 re slow Spindle 127:60 24 66 84
- 44 re slow Spindle 127:80 24 84 66
- 51 re slow Spindle 127:60 24 66 102
- 56 re slow Spindle 127:80 24 60 84
- 68 re slow Spindle 127:80 24 50 102

Test with above example of 20 TPI:
127 / 80 * 24 / 50 * 50 / 102 = 0.635 mm (ah, the gunsmiths among you will nod) 25.4mm / 0.635mm = 40 TPI !
That gearing gives you 40 TPI with the shift-gearbox set to "slow" ( 1:1 final gearing including drive spindle)
or 20 TPI with the shift-gearbox set to "medium" (1:2 final gearing including drive spindle)
or 10 TPI with the shift-gearbox set to "fast" ( 1:4 final gearing including drive spindle)

Thus, if I were an American, I'd order a 127T Modul1 sprocket from Aliexpress and would live on happily there ever after.
If I'd were Vevor, I'd ship an "US version" of the lathe with exactly that change,
or for - one box fits the world - I'd add the 127T spindle sprocket and everyone is happy.

Explanation:
"re" means gear setup to the right when viewed from the front.
"med" means medium speed selected on the spindel internal gearbox.
"slow" and "fast", I think you get the picture.

I just stumbled over your forum, so if above old news, may bad, I just wanted to share my research.


Anybody additionally need 18 TPI or 48 TPI? I recommend you get yourself a 150 teeth sprocket while ordering the 127:
(the only problem is it's hard to find a place to tack that cheat sheet onto the machine )
TPI setting_150_-10000 A B C D E
---------- ---------------------------------------------
1 mi fast Spindle 127:80 40 66 33
2 re fast Spindle 127:50 30 102 24
3 re fast Spindle 127:80 40 84 30
4 re fast Spindle 127:40 30 84 60
5 re fast Spindle 127:50 30 80 60
6 re fast Spindle 127:60 40 66 80
7 re fast Spindle 127:84 24 80 40
8 re fast Spindle 127:60 30 66 80
9 re slow Spindle 127:60 40 84 30
10 re fast Spindle 127:80 24 84 60
11 re fast Spindle 127:80 24 84 66
12 re med Spindle 127:60 40 66 80
13 re med Spindle 127:52 24 84 60
14 re fast Spindle 127:80 24 60 84
15 re slow Spindle 127:60 24 102 30
16 re med Spindle 127:60 30 66 80
17 re fast Spindle 127:80 24 50 102
18 re med Spindle 127:60 50 24 150 E2
20 re med Spindle 127:80 24 84 60
21 re med Spindle 127:60 24 66 84
22 re med Spindle 127:80 24 84 66
24 re slow Spindle 127:60 40 66 80
25 re slow Spindle 127:50 24 84 60
26 re slow Spindle 127:52 24 84 60
28 re med Spindle 127:80 24 60 84
30 re med Spindle 127:60 30 33 150 E2
32 re slow Spindle 127:60 30 66 80
33 re slow Spindle 127:60 24 80 66
34 re med Spindle 127:80 24 50 102
35 re slow Spindle 127:84 24 80 50
36 re slow Spindle 127:60 50 24 150 E2
39 re slow Spindle 127:52 40 30 150 E2
40 re slow Spindle 127:80 24 84 60
42 re slow Spindle 127:60 24 66 84
44 re slow Spindle 127:80 24 84 66
45 re slow Spindle 127:60 40 24 150 E2
48 re slow Spindle 127:80 50 24 150 E2
50 re med Spindle 127:80 24 30 150 E2
51 re slow Spindle 127:60 24 66 102
52 re slow Spindle 127:52 30 33 150 E2
56 re slow Spindle 127:80 24 60 84
60 re slow Spindle 127:60 30 33 150 E2
63 re slow Spindle 127:84 40 24 150 E2
65 re slow Spindle 127:52 24 40 150 E2
66 re slow Spindle 127:66 30 33 150 E2
68 re slow Spindle 127:80 24 50 102
75 re slow Spindle 127:60 24 33 150 E2
80 re slow Spindle 127:80 30 24 150 E2
84 re slow Spindle 127:84 30 24 150 E2
100 re slow Spindle 127:80 24 30 150 E2
102 re slow Spindle 127:102 30 24 150 E2
105 re slow Spindle 127:84 24 30 150 E2
127 re slow Spindle 127:127 30 24 150 E2

edit: that forum need a formatting that does NOT mess up ascii tables